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Topic: Decoding thermistor characteristics table (Read 2 times) previous topic - next topic

synfinatic

So as my first real Arduino project, I'm building a custom multi-temp monitor for smoking meats.  I picked up some cheap thermistor meat probes from Thermoworks and believe I tracked down the OEM to a company called Amwei.  Anyways, I'm trying to understand the information about the themistors- especially the B-value and resistance.  Some brief information about the probe is listed here (search for 'meat probe'): http://www.amwei.com/views.asp?hw_id=61

And the characteristics table is here: http://www.amwei.com/news.asp?news_id=79

I've done some tests, and I get the widest range of voltages when using a 10K resistor with it.  Does that seem reasonable? Is the beta value really 4300k?

Anyways, I'm looking into using the Thermistor4 library: http://www.arduino.cc/playground/ComponentLib/Thermistor4.  Looks like I'll have to grab my scientific calculator to figure this out!  Any help or advice would be appreciated.  Thanks!

chuckwalla

Thermistors are odd devices and its not a trivial task to get a precise temp reading with them. I've used them in the past for trip point applications. Anyways, you will need to use the Steinhart-Hart equation to calculate the temp.
Have a look at this site: http://www.facstaff.bucknell.edu/mastascu/elessonshtml/Sensors/TempR.html    I would use a thermocouple.

retrolefty

Thermocouples require low level amplification and junction compensation circuitry ($$), plus they are not all the impressive in accuracy.

Here are some info on reading thermistors from the arduino playground. http://arduino.cc/playground/ComponentLib/Thermistor2


chuckwalla

Granted TC are not as cheap as a NTC but, you don't need a $20 AD582 to used a TC either. Just a little thinking out of the box :). But, that's another post.

synfinatic

Thanks for the replies everyone.  I'm still learning about the Steinhart-Hart equation and how to apply it with a thermistor, but it seems quite doable.  The main issue I'm having is trying to understand/decode the information that Amwei has posted about the thermistor.  Basically, the data seems to be there, but I'm not sure what I'm looking at.  Any help would be greatly appreciated.

Thanks,
Aaron

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